SkelRad A Midterm Flashcards
What germ layer is bone derived from?
mesoderm
Diaphysis
primary center of ossification
epiphysis
secondary center of ossification
apophysis
secondary growth centers
a protuberance
functions as the attachment site for ligaments and tendons
Enthesis
site of attachment of tendons and ligaments
highly vascularized
high metabolic activity
What are the four functions of periosteum
attaches to the cortex via sharpey’s fibers
maintains caliber of bone by appositional bone growth
provies a transitional zone of attachment for muscles, ligament, and tendons
serves as a source of vascular perfusion for the outer third of the cortex
5 zones of the growth plate:
metaphysis zone of degeneration zone of hypertrophy zone of proliferation resting cartilage
Resting cartilage
attaches growth plate to epiphysis
if injured, growth stops
zone of proliferation
where bone is lengthened due to active growth of chondrocytes
if cells die, growth stops
zone of hypertrophy
chondrocytes mature
no active growth
weakest portion of the plate
site of salter-harris fractures
zone of degeneration
aka zone of ossification
site of dying chrondrocytes, ossification starting
attaches growth plate to metaphysis
What type of bone marrow is hematopoietically active
Red marrow
what type of bone marrow increases with age
yellow (fatty) marrow
how are calcium and phosphorous levels related?
inversely
what are the two main functions of parathormone
stimulate and control the rate of bone remodeling
influence mechanisms governing control of plasma level calcium
Two direct effects of parathormone
stimulates ca++ absorption from glomerular fluid in kidneys
promotes osteoclastic resorption in the bone
indirect effect of parathormone
influences rate of calcium absorption in the intestine
functions of vitamin d
regulates intestinal mineral absorption
maintains skeletal growth and mineralization
Vitamin D
key hormone responsible for calcium absorption from the diet
Categories of bone disease
"cat bites" congenital arthritis trauma blood (hematological) infection tumor endocrine, nutritional, metabolism soft tissue
Types of osteolytic lesions
geographic
motheaten
permeative
Characteristics of geographic lesions
destructive, sharp borders, less aggressive, slow growing, benign, narrow zone of transition
Characteristics of moth-eaten lesions
destructive, ragged borders, more rapid growth, may be malignant, 2-5 mm diameter
Punched-out lesions are characteristic of what?
multiple myeloma
characteristics of permeative lesions
ill-defined, worm holes, wide zone of transition, implies aggressive malignancy
Osteoblastic lesions
aka osteogenic
refers to a lesion that produces new bone where it should not be
A narrow zone of transition indicates what type of margin
sharp margins
A wide zone of transition indicates what type of margin
poor margins
difficult to ascertain where the lesion starts and stops
How does bone usually respond to lesions?
by making new bone
What kind of periosteal response do you usually see with a slow growing lesion?
Solid
the periosteum has plenty of time to respond to the process
can produce new bone just as fast as the lesion is growing
If a lesions grows quickly and unevenly, what type of periosteal response will you see?
lamellated aka onion skin
a pattern of one of more concentric rings of new bone over the lesion
If a lesion grows quickly and evenly, what type of periosteal response will you see?
“sunburst”
periosteum will not have time to lay down even a thin shell of bone, therefore the sharpey’s fibers become stretched out perpendicular to the bone and ossify
What will you see if the lesion grows too quickly for the periosteum to respond?
Codman’s triangle
only the edges of the raised periosteum will ossify
forms a small angle with the surface of the bone, but not a complete triangle
ddx for a solid periosteal response
benign, infection, or trauma
ddx for a lamellated periosteal response
infection or primary malignant tumor
ddx for a spiculated/sunburst periosteal response
very aggressive, primary malignant tumor
ddx for codman’s triangle
infection or primary mailgnant tumor
What are the 5 radiographic densities in radiography
air, fat, water, bone, metal
hounsfield unit
unit of radiographic density in CT gives the attenuation properties of a given tissue air = -1000 water = 0 bone = +1000
What is a bone window in CT?
differentiates medullary and cortical bone
soft tissue densities appear dark grey
What is a soft tissue window in CT?
attenuation values of soft tissues
cannot differentiate cortical and medullary bone
What is TR in MRI?
repetition time
time interval between the two 90 deg pulses
What is TE in MRI?
the time between the pulse and the detection of the MR signal
T1 MRI
short TR, short TE
shows fat
good for looking at bone marrow
T2 MRI
long TR, Long TE
shows water
good for looking at organs, or bone for trauma
Proton density MRI
long TR, short TE
all tissues
Osteoporosis
most common metabolic disease of the bone
resorption of the supporting trabeculae, spares the vertically oriented stress trabeculae
decrease in quantity, not quality
osteopenia
term used to describe general radiolucent bone
descriptive term, not a cause
Principle compressive group
part of wards triangle runs from medial metaphyseal cortex to superior femoral head major weight-bearing trabeculae thickest, most densely packed last to be obliterated
Secondary compressive group
part of wards triangle
begins near the lesser trochanter, curves toward greater trochanter
thin, widely separated
Principle tensile group
part of wards triangle
from the lateral cortex to inferior to the greater trochanter
extends in an arch like pattern
Wards triangle
confluence of three patterns, forms triangular radiolucency
Insufficiency fracture
occurs when bone is not strong enough to withstand normal physiological stress
